1. Field of the Invention
The present invention relates to a control device for electronic apparatus which can use a plurality of different kinds of power sources having different characteristics from each other.
2. Description of the Related Art
Power sources for electronic apparatus have heretofore been designed so that the electronic apparatus can be driven by means of different kinds of power sources such as batteries, electrical power lines arranged in general houses (hereinafter referred to as "AC power source"), and power sources for automobiles, as well as with a view to improving the operability of the electronic apparatus. For this reason, in many electronic apparatus, the configurations of different kinds of power sources and those of various power source adapters are designed to be the same as that of a battery, whereby each of the power sources and power source adapters can be accommodated into a common battery compartment. The tendency of adopting such a design concept is outstanding particularly in the field of portable electronic apparatus.
In such an electronic apparatus which uses a plurality of different kinds of power sources, there are some cases where a means for judging the kind of an accommodated power source is provided since individual power sources have different characteristics, capacities and so forth or in order to inform the user what kind of power source is in use.
FIG. 1 is a perspective view showing one example of a conventional battery, with FIG. 2 being a perspective view showing one example of a conventional AC power source adapter. Each of the power sources can be accommodated into a battery compartment provided in an electronic apparatus, and is arranged to effect supply of electrical power by using in common a power supplying contact provided in the body of the electronic apparatus. FIG. 3 shows a state wherein the battery is accommodated, with FIG. 4 showing a state wherein the AC power source adapter is accommodated.
In FIGS. 1 to 4, the battery is denoted by 1, and a plus electrode 1a and a minus electrode 1b are provided on the battery 1. An AC power source adapter which is used as another power supplying device is denoted by 2, and a plus electrode 2a and a minus electrode 2b are provided on the AC power source adapter 2. The AC power source adapter 2 further includes an AC power source plug 3 and a projection 2c which serves to discriminate between the battery 1 and the AC power source adapter 2. A battery compartment formed in an electronic apparatus is indicated at 4. A plus contact piece 5a, which is provided in the battery compartment 4, is connected to the plus electrode 1a of the battery 1 or the plus electrode 2a of the AC power source adapter 2. A minus contact piece 5b, which is likewise provided in the battery compartment 4, is connected to the minus electrode 1b of the battery 1 or the minus electrode 2b of the AC power source adapter 2. A micro-switch 6 is provided in the battery compartment 4, and serves to identify the kind of an accommodated power source by detecting the presence or absence of the projection 2c.
In the above-described arrangement and construction, if the battery 1 is accommodated into the battery compartment 4, as can be seen from FIG. 3, the micro-switch 6 is not switched on and remains off since no projection is formed on the battery 1. If the AC power source adapter 2 is accommodated in the battery compartment 4, an activating element of the micro-switch 6 is pressed by the projection 2c, as shown in FIG. 4, and thus the micro-switch 6 is switched on.
In this manner, on the basis of the on-off action of the micro-switch 6, it is possible to judge whether the battery 1 or the AC power source adapter 2 is accommodated in the battery compartment 4, that is, the kind of a power source.
In the above-described conventional example, however, since it is necessary to make the configuration of the battery 1 differ from that of any power supplying device other than the battery 1 in order to judge the kind of a power source, there is a need to form a large space for the battery compartment 4 in the electronic apparatus. Accordingly, the conventional example has the disadvantage that it is difficult to miniaturize the electronic apparatus. In addition, it is necessary to use as a detecting means an expensive electronic part such as a micro-switch and to strictly set the retaining structure and mounting position of the micro-switch in order to positively switch on and off the micro-switch. Accordingly, there is a disadvantage in that the construction of the electronic apparatus becomes complicated and expensive.
In the field of video tape recorders and electronic cameras which have rapidly come into wide use in recent years, in order to enable outdoor photography, it is particularly essential that such an electronic apparatus be reduced in size and weight and can be driven by a battery. In addition, the aforesaid recorders and cameras are designed so that they can use an AC power source in a place provided with the AC power source or the like in order to effect long-time recording or to reproduce and edit photographed image information for a long time.
It is also necessary that such an electronic apparatus be provided with an erasing function in order to enable a recording mode, a reproducing mode and an erasing mode for erasing unnecessary information recorded on a recording track to thereby enable re-recording on the recording track. Such modes are commonly incorporated in accordance with the range of applications of the electronic apparatus. However, since power consumption depends upon the kinds of modes incorporated, it is necessary to give consideration to the kind of a power source to be used.
Needless to say, where a battery is used as a power source, it is always necessary to give consideration to the duration of the battery. In addition, if the battery is consumed during photography and hence photographing operation becomes impossible, serious problems may occur. For example, a photographing chance may be missed or normal recording may become impossible. For this reason, it is necessary to adopt a measure for minimizing the consumption of the battery during the use thereof. However, if the capacity of the battery is merely enlarged as such a measure, the size of the battery itself and hence the weight must be increased. The resulting problem is that small size and light weight, both of which constitute features of a portable apparatus, are not attained.
Problems similar to the above-described problems occur during a reproducing mode. In general, no problem occurs in a recording mode in which the time required for one photographing cycle is short. However, in the case of reproducing operations in particular, the time period of operation varies depending upon each individual operator and, if the aforementioned recorder or camera is operated for a long time, the battery will be consumed to a great extent. For this reason, the above recorder or camera is provided with a so-called auto shut-off mechanism which is arranged to automatically switch off a power source if an inoperative state continues for a predetermined time period or more (for example, several minutes), thereby preventing the consumption of the power source and the abrasion of a head and a disc.
However, even if an AC power source whose power consumption is not a critical problem, the auto shut-off mechanism will operate in several minutes to automatically switch off the AC power source. This leads to the disadvantages that the number of operations increases, that the complexity of operation increases, and that the operability deteriorates. If the time period which elapses until the auto shut-off mechanism is started is extended in correspondence with the AC power source, or if the auto shut-off mechanism is eliminated, it is impossible to solve the above-described problem that the battery is consumed when in use. Accordingly, the use of the battery and the AC power source involves a contradictory problem.